The Doctor is In: Porosity and Itchy Scalp!

Michele writes: Hello, I have hair with low porosity, what product can I use? Sometimes I have itchy scalp too, what can I do? Thanks for your answer.

Dr. Kari Writes:

Porosity is the hair’s ability to absorb water and chemicals deep into the cortex layer of the hair strand (where all of the chemical and structural bonds are located). The hair strand has a cuticle layer that covers the strand like shingles on a roof. When the hair has a high porosity it means that this cuticle layer is lifted and there is high absorption into the cortex. Although this may sound like a benefit it is actually the opposite. Too much porosity reduces hair’s ability to retain moisture and can lead to breakage. The lifted cuticle layer allows for extra absorption, but the water evaporates just as quickly creating a much drier hair strand. The raised cuticle layer cannot hold the water inside. These dry, fragile strands break very easily, lack luster and shine and are rough to the touch.

Low porosity hair describes a hair shaft in which the cuticle scales lie flat and overlap one another. Hair with a low porosity is actually considered healthy, although you may find that the hair may feel stiff and dry due to the difficulty of absorbing moisture into the strand. Therefore, the answer to the question about “what” product is really a question of “how” to use the product and the type of ingredients to look for.

You want to use products that contain emollients (like coconut oil, avocado oil, shea butters and jojoba butters to name a few) and humectants, which attracts water from the atmosphere (e.g. glycerin). Secondly, to ensure your products absorb into the cortex layer of your hair strand use low forms of heat during the conditioning process (hooded dryer or steamer). The heat causes the cuticle layer to swell so that products can penetrate the hair strand. You can also warm up your conditioners and oils before applying it to the hair to increase the absorption.

To address your itchy scalp, you should first identify the source of the itch. Sometimes the itching is a result of a product that is causing scalp irritation. By simply changing your products, you could alleviate the itch. Ultimately, I recommend diagnosing the cause of the itch so that you can find a more effective and permanent solution to your discomfort. In the meantime, shampoos that have the active ingredient coal tar are effective. Coal tar is antipruritic and most effective when used on a consistent basis. Similar to other medicated shampoos, a coal tar shampoo should be applied directly to the scalp and allowed to sit for about 10 minutes (read the label for accurate instructions). Follow up with a moisturizing shampoo and conditioner because medicated shampoos can dry out the hair.